Gang mowers of the type described generally above should desirably be readily adjustable so as to accommodate individual mower units of different sizes, and also so as to permit rapid and convenient variation of the width of the swath cut by the apparatus. The mower apparatus should also be capable of rapid and safe movement between different job locations along roads of standard width, including roads containing potholes, ruts, rocks and the like that could damage the individual mower units if engaged thereby. Additionally, at least some and preferably all of the individual mower units should be capable of undergoing independent self-adjustive pitch, roll and twisting movements in response to undulations and other variations in the contour of the terrain traversed the assemblies.